A concentrated photovoltaic module (CPV) essentially comprises a photovoltaic cell (for example, a multi-junction cell) and a concentrator designed to concentrate solar radiation toward the cell.
In the case of a multi-junction cell, the different junctions are arranged in series, each of the junctions being adapted to a specific spectral band of solar radiation.
Multi-junction cells, which are a smaller size than conventional solar cells made of silicon, have the advantage of offering better efficiency, but in order to function, need a higher light intensity.
In a CPV module, the cells are associated with a concentrator, for example, a Fresnel lens, which concentrates solar radiation toward the cell.
Also, photovoltaic modules are designed to be mounted on a sun-follower system (also called a “tracker”) so as to optimally orient the module as a function of the trajectory of the sun so that the concentrators focus the rays of the sun onto the cells.
During manufacture of such photovoltaic modules, it is customary to verify the operation and performance of each module, with a view to detecting any failure of any one of the junctions, defects in quality or positioning of concentrators, or any other anomaly of the module before it is expedited.
The modules are frequently combined by being mounted totally or partially in series. In this case, performance of the overall system will be limited by the weakest element. It can, therefore, prove useful to select the modules before they are combined so that they are homogeneous in response. In this respect, it is important to be able to measure the performance of this module.
For this purpose, it is known to simulate the lighting of the sun by means of a lighting device generally called a “flasher,” which generates a light beam having irradiance, spectral power distribution and angular divergence close to those of the sun. These characteristics are to conform over the entire surface of the module to be tested.
CPV modules currently commercially available have relatively small dimensions (of the order of 0.5 to 1.5 m2). There are lighting devices that simulate solar lighting on a module of this type.
The Soitec company has marketed large-size solar modules, having a surface of several m2, consisting of several CPV sub-modules connected by a single chassis.
So, for example, a module of 8 m2 can be formed by two rows of six sub-modules, which can optionally be connected in series.
There is, therefore, the problem of being able to test a large-size module, since the sub-modules are connected totally or partially in series and their mechanical integrity is assured by a single chassis, they cannot be tested independently.
On the other hand, it is important to ensure the operation of the assembly before it is installed.
It is, therefore, necessary to be able to verify the performance of the complete module by simulating lighting that is as close as possible to solar radiation.
In this respect, the constraints the lighting device must respect are the following:                irradiance comparable to that produced by the sun at ground level, that is, of the order of 1 kW/m2,        reproduction of the complete solar spectrum, from ultraviolet to infrared, by respecting spectral densities,        angular divergence close to that of solar light, that is, 0.5° (±0.25°),        considerable spatial uniformity of the irradiance (the aim being inhomogeneity of irradiance less than or equal to 5%).        
Known lighting devices do not respond to these demands for a large-size module.
In fact, these devices offer either a more reduced field or characteristics (especially angular divergence) too far removed from those of the sun.
Another constraint to be considered in designing the lighting device is the compactness of the test installation.
It might be feasible to use several known devices that would illuminate each part of the module.
However, the problem arises of homogeneity of light intensity and that of the edge effects in the areas where these different devices are side by side.
In fact, not only must each device deliver very homogeneous light intensity, but this uniformity must also be respected from one lighting device to the other.
It is possible to adjust the light intensity delivered by each device by modifying the supply voltage of each source; however, this adjustment also affects the light spectrum.
An aim of this disclosure is to design a device for testing a large-size concentrated photovoltaic module that respects the constraints mentioned hereinabove, and that especially offers very good homogeneity of the light intensity, and is compatible with a compact test installation.